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The spatial extent of marine and terrestrial protected areas (PAs) was amongst the most intensely debated issues prior to the decision about the post-2020 Global Biodiversity Framework (GBF) of the Convention on Biological Diversity. Positive impacts of PAs on habitats, species diversity and abundance are well documented. Yet, biodiversity loss continues unabated despite efforts to protect 17% of land and 10% of the oceans by 2020. This casts doubt on whether extending PAs to 30%, the agreed target in the Kunming-Montreal GBF, will indeed achieve meaningful biodiversity benefits. Critically, the focus on area coverage obscures the importance of PA effectiveness and overlooks concerns about the impact of PAs on other sustainability objectives. We propose a simple means of assessing and visualising the complex relationships between PA area coverage and effectiveness and their effects on biodiversity conservation, nature-based climate mitigation and food production. Our analysis illustrates how achieving a 30% PA global target could be beneficial for biodiversity and climate. It also highlights important caveats: i) achieving lofty area coverage objectives alone will be of little benefit without concomitant improvements in effectiveness, ii) trade-offs with food production particularly for high levels of coverage and effectiveness are likely and iii) important differences in terrestrial and marine systems need to be recognized when setting and implementing PA targets. The CBD's call for a significant increase in protected area will need to be accompanied by clear PA effectiveness goals to reduce and revert dangerous anthropogenic impacts on socio-ecological systems and biodiversity.

The expert group on scenarios and models of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services initiated the development of the Nature Futures Framework for developing scenarios of positive futures for nature, to help inform assessments of policy options. This new scenarios and modelling Framework seeks to open up diversity and plurality of perspectives by differentiating three main value perspectives on nature – Nature for Nature (intrinsic values of nature), Nature for Society (instrumental values) and Nature as Culture (relational values). This paper describes how the Nature Futures Framework can be applied in modelling to support policy processes by identifying key interventions for change in realizing a diversity of desirable futures. First, the paper introduces and elaborates on key building blocks of the framework for developing qualitative scenarios and translating them into quantitative scenarios: i) multiple value perspectives on nature and the Nature Futures frontier representing diverse preferences, ii) incorporating mutual and key feedbacks of social-ecological systems in Nature Futures scenarios, and iii) indicators describing the evolution of social-ecological systems with complementary knowledge and data. This paper then presents three possible application approaches to modelling Nature Futures scenarios to support the i) review, ii) implementation and iii) design phases of policy processes. The main objective of this paper is to facilitate the integration of the relational values of nature in models, through improved indicators and other forms of evidence, and to strengthen modelled linkages across biodiversity, ecosystems, nature’s contributions to people, and quality of life to identify science- and knowledge-based interventions and to enhance ecological understanding for achieving sustainable futures. The paper aims at stimulating the development of new scenarios and models based on this new framework by a wide community of modelers, and the testing and possible further development of the framework, particularly in the context of future IPBES assessments.

International audience; The two most urgent and interlinked environmental challenges humanity faces are climate change and biodiversity loss. We are entering a pivotal decade for both the international biodiversity and climate change agendas with the sharpening of ambitious strategies and targets by the Convention on Biological Diversity and the United Nations Framework Convention on Climate Change. Within their respective Conventions, the biodiversity and climate interlinked challenges have largely been addressed separately. There is evidence that conservation actions that halt, slow or reverse biodiversity loss can simultaneously slow anthropogenic mediated climate change significantly. This review highlights conservation actions which have the largest potential for mitigation of climate change. We note that conservation actions have mainly synergistic benefits and few antagonistic trade-offs with climate change mitigation. Specifically, we identify direct co-benefits in 14 out of the 21 action targets of the draft post-2020 global biodiversity framework of the Convention on Biological Diversity, notwithstanding the many indirect links that can also support both biodiversity conservation and climate change mitigation. These relationships are context and scale-dependent; therefore, we showcase examples of local biodiversity conservation actions that can be incentivized, guided and prioritized by global objectives and targets. The close interlinkages between biodiversity, climate change mitigation, other nature's contributions to people and good quality of life are seldom as integrated as they should be in management and policy. This review aims to re-emphasize the vital relationships between biodiversity conservation actions and climate change mitigation in a timely manner, in support to major Conferences of Parties that are about to negotiate strategic frameworks and international goals for the decades to come.

There are many sources of uncertainty in scenarios and models of socio-ecological systems, and understanding these uncertainties is critical in supporting informed decision-making about the management of natural resources. Here, we review uncertainty across the steps needed to create socio-ecological scenarios, from narrative storylines to the representation of human and biological processes in models and the estimation of scenario and model parameters. We find that socio-ecological scenarios and models would benefit from moving away from “stylized” approaches that do not consider a wide range of direct drivers and their dependency on indirect drivers. Indeed, a greater focus on the social phenomena is fundamental in understanding the functioning of nature on a human-dominated planet. There is no panacea for dealing with uncertainty, but several approaches to evaluating uncertainty are still not routinely applied in scenario modeling, and this is becoming increasingly unacceptable. However, it is important to avoid uncertainties becoming an excuse for inaction in decision-making when facing environmental challenges.

World agriculture needs to find the right balance to cope with the trilemma between feeding a growing population, reducing its impact on biodiversity and minimizing greenhouse gas (GHG) emissions. In this paper, we evaluate a broad range of scenarios that achieve 4.3 GtCO2,eq/year GHG mitigation in the Agriculture, Forestry and Other Land-Use (AFOLU) sector by 2100. Scenarios include varying mixes of three GHG mitigation policies: second-generation biofuel production, dietary change and reforestation of pasture. We find that focusing mitigation on a single policy can lead to positive results for a single indicator of food security or biodiversity conservation, but with significant negative side effects on others. A balanced portfolio of all three mitigation policies, while not optimal for any single criterion, minimizes trade-offs by avoiding large negative effects on food security and biodiversity conservation. At the regional scale, the trade-off seen globally between biodiversity and food security is nuanced by different regional contexts.

Despite the scientific consensus on the extinction crisis and its anthropogenic origin, the quantification of historical trends and of future scenarios of biodiversity and ecosystem services has been limited, due to the lack of inter-model comparisons and harmonized scenarios. Here, we present a multi-model analysis to assess the impacts of land-use and climate change from 1900 to 2050. During the 20th century provisioning services increased, but biodiversity and regulating services decreased. Similar trade-offs are projected for the coming decades, but they may be attenuated in a sustainability scenario. Future biodiversity loss from land-use change is projected to keep up with historical rates or reduce slightly, whereas losses due to climate change are projected to increase greatly. Renewed efforts are needed by governments to meet the 2050 vision of the Convention on Biological Diversity.One Sentence SummaryDevelopment pathways exist that allow for a reduction of the rates of biodiversity loss from land-use change and improvement in regulating services but climate change poses an increasing challenge.

Fil: Díaz, Sandra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Diversidad Biológica y Ecología. Instituto Multidisciplinario de Biología Vegetal; Argentina. Fil: Díaz, Sandra. Consejo Nacional de Investigaciones Científicas y Técnica. Instituto Multidisciplinario de Biología Vegetal; Argentina. Fil: Zafra Calvo, Noelia. Future Earth; España. Fil: Purvis, Andy. Natural History Museum; Reino Unido. Fil: Verburg, Peter H. VU University Amsterdam. Institute for Environmental Studies: Países Bajos. Fil: Obura, David. Coastal Oceans Research and Development Indian Ocean; Kenia. Fil: Leadley, Paul. Université Paris-Sud. Ecologie Systématique Evolution; Francia. Fil: Chaplin Kramer, Rebecca. Stanford University. Natural Capital Project; Estados Unidos. Fil: De Meester, Luc. Leibniz Institut für Gewässerökologie und Binnenfischerei; Alemania. Fil: Dulloo, Ehsan. Bioversity International; Mauricio. Fil: Martín- López, Berta. Leuphana University of Lüneburg. Faculty of Sustainability; Alemania. Fil: Shaw, Rebecca. The World Wide Fund for Nature; Estados Unidos. Fil: Visconti, Piero. International Institute for Applied Systems Analysis. Ecosystem Services and Management Program; Austria. Fil: Broadgate, Wendy. Future Earth; Suecia. Fil: Bruford, Michael W. Cardiff University. School of Biosciences and Sustainable Places Institute; Reino Unido. Fil: Burgess, Neil D. UN Environment Programme World Conservation Monitoring Centre; Reino Unido. Fil: Cavender Bares, Jeannine. University of Minnesota. Department of Ecology, Evolution and Behavior; Estados Unidos. Fil: DeClerck, Fabrice. EAT Foundation; Noruega. Fil: Fernández Palacios, José María. Universidad de La Laguna. Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias; España. Fil: Garibaldi, Lucas A. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Garibaldi, Lucas A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural. Río Negro, Argentina. Fil: Hill, Samantha L. L. UN Environment Programme World Conservation Monitoring Centre; Reino Unido. Fil: Isbell, Forest. University of Minnesota. Department of Ecology, Evolution and Behavior; Estados Unidos. Fil: Khoury, Colin K. International Center for Tropical Agriculture; Colombia. Fil: Krug, Cornelia B. University of Zurich. Department of Geography; Suiza. Fil: Liu, Jianguo. Michigan State University; Estados Unidos. Fil: Maron, Martine. The University of Queensland; Australia. Fil: McGowan, Philip J. K. Newcastle University. School of Natural and Environmental Sciences; Reino Unido. Fil: Pereira, Henrique M. German Centre for Integrative Biodiversity Research; Alemania. Fil: Reyes García, Victoria. Catalan Institution for Research and Advanced Studies; España. Fil: Rocha, Juan. Future Earth; Suecia. Fil: Rondinini, Carlo. Sapienza University of Rome. Department of Biology and Biotechnologies. Global Mammal Assessment Program; Italia. Fil: Shannon, Lynne. University of Cape Town. Department of Biological Sciences; Sudáfrica. Fil: Shin, Yunne-Jai. University of Cape Town. Department of Biological Sciences; Sudáfrica. Fil: Snelgrove, Paul V. R. Memorial University of Newfoundland. Departments of Ocean Sciences and Biology; Canada. Fil: Spehn, Eva M. Swiss Academy of Sciences. Swiss Biodiversity Forum; Suiza. Fil: Strassburg, Bernardo. Pontifical Catholic University. Department of Geography and the Environment. Rio Conservation and Sustainability Science Centre; Brasil. Fil: Subramanian, Suneetha M. United Nations University. Institute for the Advanced Study of Sustainability; Japón. Fil: Tewksbury, Joshua J. University of Colorado; Estados Unidos. Fil: Watson, James E. M. Wildlife Conservation Society; Estados Unidos. Fil: Zanne, Amy E. George Washington University. Department of Biological Sciences; Estados Unidos. Global biodiversity policy is at a crossroads. Recent global assessments of living nature (1, 2) and climate (3) show worsening trends and a rapidly narrowing window for action. The Convention on Biological Diversity (CBD) has recently announced that none of the 20 Aichi targets for biodiversity it set in 2010 has been reached and only six have been partially achieved (4). Against this backdrop, nations are now negotiating the next generation of the CBD's global goals [see supplementary materials (SM)], due for adoption in 2021, which will frame actions of governments and other actors for decades to come. In response to the goals proposed in the draft post-2020 Global Biodiversity Framework (GBF) made public by the CBD (5), we urge negotiators to consider three points that are critical if the agreed goals are to stabilize or reverse nature's decline. First, multiple goals are required because of nature's complexity, with different facets—genes, populations, species, deep evolutionary history, ecosystems, and their contributions to people—having markedly different geographic distributions and responses to human drivers. Second, interlinkages among these facets mean that goals must be defined and developed holistically rather than in isolation, with potential to advance multiple goals simultaneously and minimize trade-offs between them. Third, only the highest level of ambition in setting each goal, and implementing all goals in an integrated manner, will give a realistic chance of stopping—and beginning to reverse—biodiversity loss by 2050.

Recent assessment reports by the Intergovernmental Panel on Climate Change (IPCC) and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) have highlighted the risks to humanity arising from the unsustainable use of natural resources. Thus far, land, freshwater, and ocean exploitation have been the chief causes of biodiversity loss. Climate change is projected to be a rapidly increasing additional driver for biodiversity loss. Since climate change and biodiversity loss impact human societies everywhere, bold solutions are required that integrate environmental and societal objectives. As yet, most existing international biodiversity targets have overlooked climate change impacts. At the same time, climate change mitigation measures themselves may harm biodiversity directly. The Convention on Biological Diversity’s post-2020 framework offers the important opportunity to address the interactions between climate change and biodiversity and revise biodiversity targets accordingly by better aligning these with the United Nations Framework Convention on Climate Change Paris Agreement and the Sustainable Development Goals. We identify the considerable number of existing and proposed post-2020 biodiversity targets that risk being severely compromised due to climate change, even if other barriers to their achievement were removed. Our analysis suggests that the next set of biodiversity targets explicitly addresses climate change-related risks since many aspirational goals will not be feasible under even lower-end projections of future warming. Adopting more flexible and dynamic approaches to conservation, rather than static goals, would allow us to respond flexibly to changes in habitats, genetic resources, species composition, and ecosystem functioning and leverage biodiversity’s capacity to contribute to climate change mitigation and adaptation. We acknowledge the support by Rainer Krug, Hien Ngo, and Max Gueze in parts of the literature review. Pierre Lopez drew Fig. 1, using spatial data layers provided by Aidin Niamir (https://doi.org/10.5281/zenodo.3975694).

Scenario-based modelling is a powerful tool to describe relationships between plausible trajectories of drivers, possible policy interventions, and impacts on biodiversity and ecosystem services. Model inter-comparisons are key in quantifying uncertainties and identifying avenues for model improvement but have been missing among the global biodiversity and ecosystem services modelling communities. The biodiversity and ecosystem services scenario-based inter-model comparison (BES-SIM) aims to fill this gap. We used global land-use and climate projections to simulate possible future impacts on terrestrial biodiversity and ecosystem services using a variety of models and a range of harmonized metrics. The goal of this paper is to reflect on the steps taken in BES-SIM, identify remaining methodological challenges, and suggest pathways for improvement. We identified five major groups of challenges; the need to: 1) better account for the role of nature in future human development storylines; 2) improve the representation of drivers in the scenarios by increasing the resolution (temporal, spatial and thematic) of land-use as key driver of biodiversity change and including additional relevant drivers; 3) explicitly integrate species- and trait-level biodiversity in ecosystem services models; 4) expand the coverage of the multiple dimensions of biodiversity and ecosystem services; and finally, 5) incorporate time-series or one-off historical data in the calibration and validation of biodiversity and ecosystem services models. Addressing these challenges would allow the development of more integrated global projections of biodiversity and ecosystem services, thereby improving their policy relevance in supporting the interlinked international conservation and sustainable development agendas.

Scenarios are powerful tools toenvision how nature might respondto different pathways of futurehuman development and policy choices1.Most scenarios developed for globalenvironmental assessments have exploredimpacts of society on nature, such asbiodiversity loss, but have not includednature as a component of socioeconomicdevelopment2. They ignore policyobjectives related to nature protectionand neglect nature?s role in underpinningdevelopment and human well-being.This approach is becoming untenablebecause targets for human developmentare increasingly connected with targetsfor nature, such as in the United Nations?Sustainable Development Goals. The nextgeneration of scenarios should explorealternative pathways to reach theseintertwined targets, including potentialsynergies and trade-offs between natureconservation and other developmentgoals, as well as address feedbacks betweennature, nature?s contributions to people,and human well-being. The developmentof these scenarios would benefit from theuse of participatory approaches, integratingstakeholders from multiple sectors (forexample, fisheries, agriculture, forestry)and should address decision-makersfrom the local to the global scale3, therebysupporting assessments being undertakenby the Intergovernmental Platformon Biodiversity and EcosystemServices (IPBES). Fil: Rosa, Isabel M. D.. German Centre For Integrative Biodiversity Research; Alemania. Martin-universitat Halle-wittenberg; Alemania Fil: Pereira, Henrique M.. German Centre For Integrative Biodiversity Research; Alemania. Martin-universitat Halle-wittenberg; Alemania. Universidad de Porto; Portugal Fil: Ferrier, Simon. Csiro Land And Water; Australia Fil: Alkemade, Rob. Pbl Netherlands Environmental Assessment Agency; Países Bajos Fil: Acosta, Lilibeth A.. University Of The Philippines Los Banos; Filipinas Fil: Akcakaya, H. Resit. Stony Brook University; Estados Unidos Fil: Den Belder, Eefje. Pbl Netherlands Environmental Assessment Agency; Países Bajos. Wageningen University And Research Centre; Países Bajos Fil: Fazel, Asghar M.. Eco Institute Of Environmental Science And Technology; Irán. University Of Environment; Irán Fil: Fujimori, Shinichiro. International Institute For Applied Systems Analysis; Austria. National Institute For Environmental Studies Of Japan; Japón Fil: Harfoot, Mike. United Nations Environment Programme World Conservation Monitoring Centre; Reino Unido Fil: Harhash, Khaled A.. Egyptian Environmental Affairs Agency; Egipto Fil: Harrison, Paula A.. Lancaster University; Reino Unido Fil: Hauck, Jennifer. Coknow Consulting; Alemania. Helmholtz Centre for Environmental Research; Alemania Fil: Hendriks, Rob J. J.. Ministry Of Economic Affairs; Países Bajos Fil: Hernández, Gladys. Centre For World Economy Studies; Cuba Fil: Jetz, Walter. Imperial College London; Reino Unido. University of Yale; Estados Unidos Fil: Karlsson Vinkhuyzen, Sylvia I.. Wageningen University And Research Centre; Países Bajos Fil: Kim, Hyejin. National Institute Of Ecology; Corea del Sur Fil: King, Nicholas. North-west University; Sudáfrica Fil: Kok, Marcel T. J.. Pbl Netherlands Environmental Assessment Agency; Países Bajos Fil: Kolomytsev, Grygoriy O.. Schmalhausen Institute of Zoology of National Academy of Sciences of Ukrain; Ucrania Fil: Lazarova, Tanya. Pbl Netherlands Environmental Assessment Agency; Países Bajos Fil: Leadley, Paul. Université Paris Sud; Francia Fil: Lundquist, Carolyn J.. National Institute Of Water And Atmospheric Research; Nueva Zelanda. The University of Auckland; Nueva Zelanda Fil: García Márquez, Jaime. Humboldt-Universität zu Berlin; Alemania Fil: Meyer, Carsten. German Centre For Integrative Biodiversity Research; Alemania. University of Yale; Estados Unidos Fil: Navarro, Laetitia M.. German Centre For Integrative Biodiversity Research; Alemania. Martin-universitat Halle-wittenberg; Alemania Fil: Nesshöver, Carsten. Helmholtz Centre for Environmental Research; Alemania. German Centre for Integrative Biodiversity Research; Alemania Fil: Ngo, Hien T.. Ipbes Secretariat; Alemania Fil: Ninan, Karachepone N.. Centre For Economics, Environment And Society; India Fil: Palomo, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Pereira, Laura M.. Stockholms Universitet; Suecia Fil: Peterson, Garry D.. Stockholms Universitet; Suecia Fil: Pichs, Ramon. Centre For World Economy Studies; Cuba Fil: Popp, Alexander. Potsdam Institute for Climate Impact Research; Alemania Fil: Purvis, Andy. Natural History Museum; Reino Unido Fil: Ravera, Federica. Consejo Superior de Investigaciones Científicas. Centre de Recerca Ecológica I Aplicacions Forestals; España. University Of Évora; Portugal. Universitat Central De Catalunya; España Fil: Rondinini, Carlo. Università degli studi di Roma "La Sapienza"; Italia Fil: Sathyapalan, Jyothis. Centre For Economic And Social Studies; India Fil: Schipper, Aafke M.. Pbl Netherlands Environmental Assessment Agency; Países Bajos Fil: Seppelt, Ralf. Coknow Consulting; Alemania. Martin Luther University Halle-Wittenberg; Alemania Fil: Settele, Josef. German Centre for Integrative Biodiversity Research; Alemania. Helmholtz Centre for Environmental Research; Alemania Fil: Sitas, Nadia. The Council For Scientific And Industrial Research; Sudáfrica Fil: Van Vuuren, Detlef. Pbl Netherlands Environmental Assessment Agency; Países Bajos

Global and regional climate model (GCM and RCM) outputs are often used as climate forcing for ecological impact models, and this potentially results in large cumulative errors because information and error are passed sequentially along the modeling chain from GCM to RCM to impact model. There are also a growing number of Earth system modeling platforms in which climate and ecological models are dynamically coupled, and in this case error amplification due to feedbacks can lead to even more serious problems. It is essential in both cases to rethink the organization of evaluation which typically relies on independent validation at each successive step, and to rely more heavily on analyses that cover the full modeling chain and thus require stronger interactions between climate and impact modelers. In this paper, we illustrate the benefits of using impact models as an additional source of information for evaluating climate models. Four RCMs that are part of the HyMeX (Hydrological cycle in Mediterranean EXperiment) and Mediterranean CORDEX projects (MED-CORDEX) were tested with observed climatology and a process-based model of European beech (Fagus sylvatica L.) tree growth and forest ecosystem functioning that has been rigorously validated. This two part analysis i) indicates that evaluation of RCMs on climate variables alone may be insufficient to determine the suitability of RCMs for studies of climate-forest interactions and ii) points to areas of improvement in these RCMs that would improve impact studies or behavior in coupled climate-ecosystem models over the spatial domain studied. © 2015, Springer Science+Business Media Dordrecht.

In 2010, the parties of the Convention on Biological Diversity (CBD) adopted the Strategic Plan for Biodiversity 2011–2020 with the mission of halting biodiversity loss and enhance the benefits it provides to people. The 20 Aichi Biodiversity Targets (Aichi Targets), which are included in the Strategic Plan, are organized under five Strategic Goals, and provide coherent guidance on how to achieve it. Halfway through the Strategic Plan, it is time to prioritize actions in order to achieve the best possible outcomes for the Aichi Targets in 2020. Actions to achieve one target may influence other targets (downstream interactions); in turn a target may be influenced by actions taken to attain other targets (upstream interactions). We explore the interactions among targets and the time-lags between implemented measures and desired outcomes to develop a framework that can reduce the overall burden associated with the implementation of the Strategic Plan. We identified the targets addressing the underlying drivers of biodiversity loss and the targets aimed at enhancing the implementation of the Strategic Plan as having the highest level of downstream interactions. Targets aimed at improving the status of biodiversity and safeguarding ecosystems followed by targets aimed at reducing the direct pressures on biodiversity and enhancing the benefits to all from biodiversity and ecosystem services, were identified as having the highest levels of upstream interactions. Perhaps one of the most challenging aspects of the Strategic Plan is the need to balance actions for its long-term sustainability with the need for urgent actions to halt biodiversity loss.

Current trajectories of global change may lead to regime shifts at regional scales, driving coupled human-environment systems to highly degraded states in terms of biodiversity, ecosystem services, and human well-being. For business-as-usual socioeconomic development pathways, regime shifts are projected to occur within the next several decades, to be difficult to reverse, and to have regional- to global-scale impacts on human society. We provide an overview of ecosystem, socioeconomic, and biophysical mechanisms mediating regime shifts and illustrate how these interact at regional scales by aggregation, synergy, and spreading processes. We give detailed examples of interactions for terrestrial ecosystems of central South America and for marine and coastal ecosystems of Southeast Asia. This analysis suggests that degradation of biodiversity and, ecosystem services over the twenty-first century could be far greater than was previously predicted. We identify key policy and management opportunities at regional to global scales to avoid these shifts.

International audience

International audience

DIVERSITAS, the international programme on biodiversity science, is releasing a strategic vision presenting scientific challenges for the next decade of research on biodiversity and ecosystem services: “Biodiversity and Ecosystem Services Science for a Sustainable Planet”. This new vision is a response of the biodiversity and ecosystem services scientific community to the accelerating loss of the components of biodiversity, as well as to changes in the biodiversity science-policy landscape (establishment of a Biodiversity Observing Network — GEO BON, of an Intergovernmental science-policy Platform on Biodiversity and Ecosystem Services — IPBES, of the new Future Earth initiative; and release of the Strategic Plan for Biodiversity 2011–2020). This article presents the vision and its core scientific challenges. Fil: Larigauderie, Anne. DIVERSITAS. Muséum National d’Histoire Naturelle; Francia Fil: Prieur Richard, Anne Helene. DIVERSITAS. Muséum National d’Histoire Naturelle; Francia Fil: Mace, Georgina. Imperial College London. Center for Population Biology; Reino Unido Fil: Londsdale, Mark. CSIRO Ecosystem Sciences; Australia Fil: Mooney, Harold A.. Stanford University. Department of Biological Sciences; Estados Unidos Fil: Brussaard, Lijbert. Wageningen University, Soil Quality Department; Países Bajos Fil: Cooper, David. Secretariat of the Convention on Biological Diversity; Canadá Fil: Wolfgang, Cramer. Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale; Francia Fil: Daszak, Peter. EcoHealth Alliance. Wildlife Trust; Estados Unidos Fil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Duraiappah, Anantha. International Human Dimensions Programme; Alemania Fil: Elmqvist, Thomas. University of Stockholm. Department of Systems Ecology and Stockholm Resilience Center; Suecia Fil: Faith, Daniel. The Australian Museum; Australia Fil: Jackson, Louise. University of California; Estados Unidos Fil: Krug, Cornelia. DIVERSITAS. Muséum National d’Histoire Naturelle; Francia Fil: Leadley, Paul. Université Paris. Laboratoire Ecologie Systématique Evolution, Ecologie des Populations et Communautés; Francia Fil: Le Prestre, Philippe. Laval University; Canadá Fil: Matsuda, Hiroyuki. Yokohama National University; Japón Fil: Palmer, Margaret. University of Maryland; Estados Unidos Fil: Perrings, Charles. Arizona State University; Estados Unidos Fil: Pulleman, Mirjam. Wageningen University; Países Bajos Fil: Reyers, Belinda. Natural Resources and Environment; Sudáfrica Fil: Rosa, Eugene A.. Washington State University; Estados Unidos Fil: Scholes, Robert J.. Natural Resources and Environment; Sudáfrica Fil: Spehn, Eva. Universidad de Basilea; Suiza Fil: Turner II, B. L.. Arizona State University; Estados Unidos Fil: Yahara, Tetsukazu. Kyushu University; Japón

International audience; Global environmental changes are expected to alter ecosystem carbon and nitrogen cycling, but the interactive effects of multiple simultaneous environmental changes are poorly understood. Effects of these changes on the production of nitrous oxide (N2O), an important greenhouse gas, could accelerate climate change. We assessed the responses of soil N2O fluxes to elevated CO2, heat, altered precipitation, and enhanced nitrogen deposition, as well as their interactions, in an annual grassland at the Jasper Ridge Global Change Experiment (CA, USA). Measurements were conducted after 6, 7 and 8 years of treatments. Elevated precipitation increased N2O efflux, especially in combination with added nitrogen and heat. Path analysis supported the idea that increased denitrification due to increased soil water content and higher labile carbon availability best explained increased N2O efflux, with a smaller, indirect contribution from nitrification. In our data and across the literature, single-factor responses tended to overestimate interactive responses, except when global change was combined with disturbance by fire, in which case interactive effects were large. Thus, for chronic global environmental changes, higher order interactions dampened responses of N2O efflux to multiple global environmental changes, but interactions were strongly positive when global change was combined with disturbance. Testing whether these responses are general should be a high priority for future research.

Plant growth and development is dependent on factors internal and external to the plant. The effect of nutrient on root morphology has been widely studied in artificial soils or solution cultures. However, the effect of this experimental procedure has never been assessed by comparing plant response in artificial and natural soils. In a laboratory experiment, plants were submitted to three levels of nitrogen supply, in one artificial substratum made of pure sand and one natural soil. Deep differences in plant homeostasis, growth and development were observed between natural and artificial soils: (i) the chemical composition of plant tissues (%C and %N) was changing according to the nitrogen gradient in the artificial substratum, whereas it remained constant in the natural soil; (ii) the same amount of added nitrogen was responsible for a 17% increase in total plant production in the natural soil as compared with the artificial substratum; (iii) plant development differed deeply in the two substrata: in the artificial substratum, the shoot to root ratio was stable whereas the thick to fine roots ratio was increasing with increasing N supply, suggesting an exploration strategy to found an absent limiting nutrient. Conversely, in the natural soil, the thick to fine roots ratio was stable whereas the shoot to root ratio was decreasing with increasing N supply, suggesting an exploitation strategy dedicated to extract a limiting nutrient present in soil components. Even if mechanisms responsible for changes in homeostasis, growth and development were not elucidated, these results stress the importance to consider substrata with a minimal level of complexity if we expect to understand plant growth and development in natural conditions thanks to laboratory experiments.

Background: Little is known about the combined impacts of global environmental changes and ecological disturbances on ecosystem functioning, even though such combined impacts might play critical roles in shaping ecosystem processes that can in turn feed back to climate change, such as soil emissions of greenhouse gases.[br/] Methodology/Principal Findings: We took advantage of an accidental, low-severity wildfire that burned part of a long-term global change experiment to investigate the interactive effects of a fire disturbance and increases in CO(2) concentration, precipitation and nitrogen supply on soil nitrous oxide (N(2)O) emissions in a grassland ecosystem. We examined the responses of soil N(2)O emissions, as well as the responses of the two main microbial processes contributing to soil N(2)O production - nitrification and denitrification - and of their main drivers. We show that the fire disturbance greatly increased soil N(2)O emissions over a three-year period, and that elevated CO(2) and enhanced nitrogen supply amplified fire effects on soil N(2)O emissions: emissions increased by a factor of two with fire alone and by a factor of six under the combined influence of fire, elevated CO(2) and nitrogen. We also provide evidence that this response was caused by increased microbial denitrification, resulting from increased soil moisture and soil carbon and nitrogen availability in the burned and fertilized plots. [br/] Conclusions/Significance: Our results indicate that the combined effects of fire and global environmental changes can exceed their effects in isolation, thereby creating unexpected feedbacks to soil greenhouse gas emissions. These findings highlight the need to further explore the impacts of ecological disturbances on ecosystem functioning in the context of global change if we wish to be able to model future soil greenhouse gas emissions with greater confidence.

International audience; Responses of soil nitrogen (N) cycling to simultaneous and potentially interacting global environmental changes are uncertain. Here, we investigated the combined effects of elevated CO2, warming, increased precipitation and enhanced N supply on soil N cycling in an annual grassland ecosystem as part of the Jasper Ridge Global Change Experiment (CA, USA). This field experiment included four treatments—CO2, temperature, precipitation, nitrogen—with two levels per treatment (ambient and elevated), and all their factorial combinations replicated six times. We collected soil samples after 7 and 8 years of treatments, and measured gross rates of N mineralization, N immobilization and nitrification, along with potential rates of ammonia oxidation, nitrite oxidation and denitrification. We also determined the main drivers of these microbial activities (soil ammonium and nitrate concentrations, soil moisture, soil temperature, soil pH, and soil CO2 efflux, as an indicator of soil heterotrophic activity). We found that gross N mineralization responded to the interactive effects of the CO2, precipitation and N treatments: N addition increased gross N mineralization when CO2 and precipitation were either both at ambient or both at elevated levels. However, we found limited evidence for interactions among elevated CO2, warming, increased precipitation, and enhanced N supply on the other N cycling processes examined: statistically significant interactions, when found, tended not to persist across multiple dates. Soil N cycling responded mainly to single-factor effects: long-term N addition increased gross N immobilization, potential ammonia oxidation and potential denitrification, while increased precipitation depressed potential nitrite oxidation and increased potential ammonia oxidation and potential denitrification. In contrast, elevated CO2 and modest warming did not significantly affect any of these microbial N transformations. These findings suggest that global change effects on soil N cycling are primarily additive, and therefore generally predictable from single factor studies.

International audience; Climate change effects on tree function, structure and growth have been observed in various forests throughout Europe and France in the last decades. Forest productivity and survival are limited by a variety of environmental abiotic factors such as soil nutrients, temperature, atmospheric CO2 concentration, and water balance. Differential impacts of global climatic changes on forests, as well as complex interactions with the carbon and water balance, and vegetation feedbacks on climate makes it hard to estimate future vegetation patterns. Obtaining reliable predictions of species range shifts under climate change is a crucial challenge for ecologists and stakeholders. However, it is evident that no single modelling procedure can provide appropriate predictions in the future. Model comparison is a powerful tool to evaluate models in a more conceptual way by comparing and interpreting predictions on the basis of the underlying model approaches and assumptions. This work aims at understanding future spatial distribution, physiological response and potential adaptation of 7 species in France under future climate, by using and comparing simulations stemming from different model concepts. Here, we present only the results for Temperate broadleaf species (Fagus sylvatica and Quercus robur) and compare predictions of range shifts under climate change scenarios for 2050 derived from three niche-based models (BIOMOD, NBM and STASH) with those derived from a mechanistic tree growth process-based model (CASTANEA), a phenology-based model (PHENOFIT) and three dynamic global vegetation model DGVM (LPJ, ORCHIDEE and IBIS). A contrasted pattern emerged from our comparisons: although all models project significant losses ofT emperate broadleaf species range in France in 2050, significant divergences between models appear: niche-based models tend to predict a stronger level of range loss in the plains across France than the other models, and they project less range loss in mountains than in lowlands. LPJ projects the smallest loss of range in plains and increased presence of beech in mountains. In general, LPJ, Orchidee, Castanea and PhenoFit are more conservative in the North, East and North-East of France than in the South, West and South West. This result likely arises because niche-based models do not take complex interactions between physiological processes and climate, phenotypic plasticity, and local adaptation into account. Nevertheless, there is much greater uncertainty in projected tree response to climate change than previous studies have suggested. This means that forest management must focus on dealing with an uncertain future, i.e., by increasing the resilience of forest ecosystems.

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.

International audience; Future climate scenarios predict simultaneous changes in environmental conditions, but the impacts of multiple climate change drivers on ecosystem structure and function remain unclear. We used a novel experimental approach to examine the responses of an upland grassland ecosystem to the 2080 climate scenario predicted for the study area (3.5A degrees C temperature increase, 20% reduction in summer precipitation, atmospheric CO2 levels of 600 ppm) over three growing seasons. We also assessed whether patterns of grassland response to a combination of climate change treatments could be forecast by ecosystem responses to single climate change drivers. Effects of climate change on aboveground production showed considerable seasonal and interannual variation; April biomass increased in response to both warming and the simultaneous application of warming, summer drought, and CO2 enrichment, whereas October biomass responses were either non-significant or negative depending on the year. Negative impacts of summer drought on production were only observed in combination with a below-average rainfall regime, and showed lagged effects on spring biomass. Elevated CO2 had no significant effect on aboveground biomass during this study. Both warming and the 2080 climate change scenario were associated with a significant advance in flowering time for the dominant grass species studied. However, flowering phenology showed no significant response to either summer drought or elevated CO2. Species diversity and equitability showed no response to climate change treatments throughout this study. Overall, our data suggest that single-factor warming experiments may provide valuable information for projections of future ecosystem changes in cool temperate grasslands.

Despite increasing interest in the effects of climate change on soil processes, the response of nitrification to elevated CO2 remains unclear. Responses may depend on soil nitrogen (N) status, and inferences may vary depending on the methodological approach used. We investigated the interactive effects of elevated CO2 and inorganic N supply on gross nitrification (using 15N pool dilution) and potential nitrification (using nitrifying enzyme activity assays) in Dactylis glomerata mesocosms. We measured the responses of putative drivers of nitrification (NH 4 + production, NH 4 + consumption, and soil environmental conditions) and of potential denitrification, a process functionally linked to nitrification. Gross nitrification was insensitive to all treatments, whereas potential nitrification was higher in the high N treatment and was further stimulated by elevated CO2 in the high N treatment. Gross mineralization and NH 4 + consumption rates were also significantly increased in response to elevated CO2 in the high N treatment, while potential denitrification showed a significant increase in response to N addition. The discrepancy between the responses of gross and potential nitrification to elevated CO2 and inorganic N supply suggest that these measurements provide different information, and should be used as complementary approaches to understand nitrification response to global change.

International audience; Plant-plant and plant-soil interactions play a key role in determining plant community structure and ecosystem function. However, the effects of global change on the interplay between co-occurring plants and soil microbes in successional communities are poorly understood. In this study, we investigated competition for nitrogen (N) between soil microorganisms, grass plants and establishing tree seedlings under factorial carbon dioxide (CO2) and N treatments. Fruxinus excelsior seedlings were germinated in the presence or absence of grass competition (Dacrylis glomerata) at low (380 mu mol mol(-1)) or high (645 mu mol mol(-1)) CO2 and at two levels of N nutrition in a mesocosm experiment. Pulse N-15 labelling was used to examine N partitioning among plant and soil compartments. Dactylis exerted a strong negative effect on Fraxinus biomass, N capture and N-15 recovery irrespective of N and CO2 treatment. In contrast, the presence of Dactylis had a positive effect on the microbial N pool. Plant and soil responses to N treatment were of a greater magnitude compared with responses to elevated CO2, but the pattern of Fraxinus- and microbial-N pool response to N and CO2 varied depending on grass competition treatment. Within the Dactylis competition treatment, decreases in Fraxinus biomass in response to N were not mirrored by decreases in tree seedling N content, suggesting a shift from below- to above-ground competition. In the Dactylis-sown pots, N-15 recovery could be ranked Dactylis > microbial pool > Fraxinus in all N and CO2 treatment combinations. Inequalities between Fraxinus and soil microorganisms in terms of N-15 recovery were exacerbated by N addition. Contrary to expectations, elevated CO2 did not increase plant-microbe competition. Nevertheless, microbial N-15 recovery showed a small positive increase in the high CO2 treatment. Overall, elevated CO2 and N supply did not interact on plant/soil N partitioning. Our data suggest that the competitive balance between establishing tree seedlings and grass plants in an undisturbed sward is relatively insensitive to CO2 or N-induced modifications in N competition between plant and soil compartments.

International audience; Plants modify nutrient availability by releasing chemicals in the rhizosphere. This change in availability induced by roots (bioavailability) is known to improve nutrient uptake by individual plants releasing such compounds. Can this bioavailability alter plant competition for nutrients and under what conditions? To address these questions, we have developed a model of nutrient competition between plant species based on mechanistic descriptions of nutrient diffusion, plant exudation, and plant uptake. The model was parameterized using data of the effects of root citrate exudation on phosphorus availability. We performed a sensitivity analysis for key parameters to test the generality of these effects. Our simulations suggest the following. ( 1) Nutrient uptake depends on the number of roots when nutrients and exudates diffuse little, because individual roots are nearly independent in terms of nutrient supply. In this case, bioavailability profits only species with exudates. ( 2) Competition for nutrients depends on the spatial arrangement of roots when nutrients diffuse little but exudates diffuse widely. ( 3) Competition for nutrients depends on the nutrient uptake capacity of roots when nutrients and exudates diffuse widely. In this case, bioavailability profits all species. Mechanisms controlling competition for bioavailable nutrients appear to be diverse and strongly depend on soil, nutrient, and plant properties.

International audience; The competitive interactions between woody seedlings and herbaceous vegetation have received increasing interest in recent years. However, little is known about the relative contributions and underlying mechanisms of above- and below-ground competition between species. We used a novel experimental approach to assess the responses of Fraxinus excelsior seedlings to different combinations of root and shoot competition imposed by the grass Dactylis glomerata under greenhouse conditions. Seedling growth was significantly reduced by competition for soil resources, but neither biomass nor height were significantly affected by shoot competition for light. Competitive response indices based on biomass confirmed that below-ground competition was more important than above-ground competition, and indicated that root and shoot competition did not interact to influence plant growth. Fraxinus biomass allocation and seedling traits were almost all significantly affected by root competition; these responses varied depending on the trait examined. In contrast, morphological responses to shoot competition were limited. In the absence of root competition, seedlings showed a significant increase in the biomass allocated to leaves and a greater leaf area ratio in response to shoot competition. Our findings suggest that morphological modifications help to mitigate the negative effects of competition, but the expression of plasticity may be suboptimal due to resource constraints. The present study also highlights the importance of appropriate experimental controls and analysis to avoid confounding effects of experimental design and ontogeny on the interpretation of competitive responses.

Biodiversity and ecosystem functioning research has been some of the most controversial of the last decade but rapid progress has been made by deriving hypotheses from the differing view points and challenging them with appropriate experimental and analytical tests (Loreau et al. 2001). Here we address some recent criticisms of the BIODEPTH project (Thompson et al. 2005) and show that: 1. While legume species play an important role in the BIODEPTH results, patterns are not generally consistent with the multispecies sampling effect for legumes proposed by Huston & McBride (2002) as suggested in Thompson et al. (2005). 2. The BIODEPTH results are also not consistent with transient biodiversity effects. Levels of species diversity were generally maintained over the 3 years of the project (i.e. little competitive exclusion) and diversity-productivity relationships in BIODEPTH generally strengthened during the experiments.

We have developed a spatially explicit model of plant root and soil bacteria interactions in the rhizosphere in order to formalise and study the microbial loop hypothesis that postulates that plants can stimulate the release of mineral N from the soil organic matter by providing low molecular weight C molecules to C-limited microorganisms able to liberate into the soil enzymes that degrade the organic matter. The model is based on a mechanistic description of diffusion of solutes in the soil, nutrient uptake by plants, bacterial activity and bacterial predation. Modelled soil bacterial populations grow, mediate transformations among several forms of nitrogen (mineral and organic) and compete for nitrogen with plants. Our objectives were to see if we could simulate the stimulation of turnover of the microbial loop by exudates and to study the effects of diffusion of C and N in the rhizosphere on these different processes. The model qualitatively mimics most of the characteristics of the microbial loop hypothesis. In particular, (1) plant exudates increase the growth of bacteria in the soil and (2) increase the degradation of soil organic matter and N mineralisation. (3) The increased bacterial biomass induces an increase in predator biomass and, as a result, (4) plant mineral N uptake is increased threefold compared with scenarios without exudation. However, the temporal dynamics simulated by the model are much slower than observed dynamics (the increase in uptake appears after a few months). Taking into consideration the diffusion of C and N containing molecules in soil has large effects on the spatial structure of the bacterial and predator biomass. However, the average biomass of bacteria and predators, N mineralisation and plant N uptake were not affected by these properties. The model provides a quantitative and mechanistic explanation of how plants could benefit from liberating low molecular organic matter and the subsequent stimulation of the microbial loop and increases N mineralisation.

Plant and Soil, 280 (1-2), ISSN:0032-079X, ISSN:1573-5036

International audience; The effects of global change on below-ground processes of the nitrogen (N) cycle have repercussions for plant communities, productivity and trace gas effluxes. However, the interacting effects of different components of global change on nitrification or denitrification have rarely been studied in situ. 2. We measured responses of nitrifying enzyme activity (NEA) and denitrifying enzyme activity (DEA) to over 4 years of exposure to several components of global change and their interaction (increased atmospheric CO2 concentration, temperature, precipitation and N addition) at peak biomass period in an annual grassland ecosystem. In order to provide insight into the mechanisms controlling the response of NEA and DEA to global change, we examined the relationships between these activities and soil moisture, microbial biomass C and N, and soil extractable N. 3. Across all treatment combinations, NEA was decreased by elevated CO2 and increased by N addition. While elevated CO2 had no effect on NEA when not combined with other treatments, it suppressed the positive effect of N addition on NEA in all the treatments that included N addition. We found a significant CO2-N interaction for DEA, with a positive effect of elevated CO2 on DEA only in the treatments that included N addition, suggesting that N limitation of denitrifiers may have occurred in our system. Soil water content, extractable N concentrations and their interaction explained 74% of the variation in DEA. 4. Our results show that the potentially large and interacting effects of different components of global change should be considered in predicting below-ground N responses of Mediterranean grasslands to future climate changes.

We studied the symmetry of belowground competition at the level of species using a model of plant competition at the scale of individual roots. This model predicts the nutrient uptake of plants with varying root densities and uptake kinetics, competing for the same resource, at equilibrium between resource supply and plant uptake. A symmetry parameter is derived from this model. The analysis of the model behaviour suggests that the symmetry of belowground competition depends on the diffusive supply of the nutrient (buffer capacity × effective diffusion coefficient) for which competition occurs. As the diffusive supply is determined to a greater extent by soil water content and soil type rather than by nutrient type, this means that the symmetry of belowground competition should vary with soil water content and soil type. In particular, our model suggests that competition for nutrients that are primarily supplied by diffusion through the soil is (1) symmetrical at high diffusive supply when root uptake kinetics are identical or at low diffusive supply when roots are randomly distributed in the soil whatever their uptake kinetics are, (2) size-asymmetrical at high diffusive supply when root uptake kinetics are different, (3) partially symmetric or size-asymmetric at low diffusive supply when root are not randomly distributed in the soil.

Soil and nutrient properties, via their influence on nutrient diffusion rates in the soil, may play a key role in determining the outcome of plant competition for nutrients. We used two models to explore the potential contributions of nutrient uptake kinetics, root density, soil properties, and nutrient type to interspecific plant competition for soil nutrients. The first model uses well-known nutrient diffusion and absorption relationships to generate soil nutrient concentration maps and nutrient uptake at the scale of individual roots (PARIS- M). A second model (PARIS-E) was developed based on a fit of the Hill equation to the output of PARIS-M. The PARIS-E model provides an accurate and simple means of de- termining the relative contributions of sink strength (root surface area X uptake kinetics) vs. space occupation (number of roots per unit area) to competition at equilibrium as modeled by PARIS-M. An analysis based on these two models suggests the following: (1) Diffusive supply (soil nutrient buffer capacity x effective diffusion coefficient) determines the relative im- portance of space occupation vs. sink strength for nutrient competition. (2) At the low range of reported values of diffusive supply, competition depends on space occupation and, therefore, the species with the most roots per unit area is the most competitive. Sink strength gains in importance as diffusive supply increases and dominates competitive interactions at the high end of the range of reported diffusive supplies. (3) The relative importance of space occupation vs. sink strength depends primarily on soil water content and soil texture, because diffusive supply is sensitive to these factors. Diffusive supply is relatively insen- sitive to nutrient type. This analysis suggests that nutrient competition models should include the effects of soil properties as a determinant of the relative contributions of sink strength vs. space occupation.

Summary • The objective of this study was to better identify the mechanisms by which elevated CO2 (c. 665 µmol mol−1) alters soil nitrifying and denitrifying enzyme activity (NEA and DEA), and the dynamics of plant and microbial N pools. • We measured the effects of elevated CO2 on plant biomass and N, soil microbial biomass N, soil ammonium and nitrate concentrations, NEA and DEA in monospecific grassland mesocosms (Holcus lanatus and Festuca rubra) grown for 15 months in reconstituted grassland soil. • NEA strongly decreased at elevated CO2 in the Holcus mesocosms, but was not affected in Festuca systems. DEA was less sensitive to elevated CO2 than NEA. In Holcus mesocosms, microbial N showed an initial growth phase that appeared to limit plant N acquisition, but was only transient. • CO2-induced changes in NEA and DEA were best explained by factors that could reduce soil [O2] (increased soil water content and organic C). Elevated CO2 may increase microbial immobilisation in highly disturbed systems, this effect weakening as the system gets closer to equilibrium.

Plant nutrient responses to 4 years of CO2 enrichment were investigated in situ in calcareous grassland. Beginning in year 2, plant aboveground C:N ratios were increased by 9% to 22% at elevated CO2 (P > 0.01), depending on year. Total amounts of N removed in biomass harvests during the first 4 years were not affected by elevated CO2 (19.9 +/- 1.3 and 21.1 +/- 1.3 g N m(-2) at ambient and elevated CO2), indicating that the observed plant biomass increases were solely attained by dilution of nutrients. Total aboveground P and tissue N:P ratios also were not altered by CO2 enrichment (12.5 +/- 2 g N g(-1) P in both treatments). In contrast to non-legumes (

PhD thesis of Criscely LUJÁN PAREDES about uncertainty in complex models, applied to the OSMOSE ecosystem model of the northern Humboldt current system. The PhD was supervised by Paul LEADLEY, Yunne-Jai SHIN and Ricardo OLIVEROS-RAMOS